Notification of Dropped Audio in a Teleconference Call

ABSTRACT

A method is disclosed that enables a participant in a conference call to monitor, as he is speaking, whether his speech is getting through to the other participants. A teleconference bridge receives audio signals from a group of telecommunications endpoints that are involved in a conference call. The bridge generates audio signals to be transmitted, which are based on one or more of the received audio signals. During the ongoing process of minimizing the presence of acoustic echo, the bridge might exclude one or more of the received audio signals from the transmitted audio signals. When this occurs, particularly when an active talker is being excluded, the bridge transmits an indication to one or more of the endpoints as part of one of the transmitted audio signals. The indication can be audible such as a tone or a voice, visual such as a flashing light, or tactile such as vibration.

FIELD OF THE INVENTION

The present invention relates to telecommunications in general, and,more particularly, to notifying one or more users of telecommunicationsendpoints that their audio signals are being dropped during a conferencecall.

A teleconferencing system enables concurrent communication among threeor more participants. Typically, such a system comprises ateleconference bridge, which mixes the audio signals arriving from thetelecommunications endpoints of the participants and transmits anappropriately-mixed signal back to each of the endpoints. The endpointsthemselves might be handset-equipped telephones or they might bespeakerphone-equipped telephones, or a combination of the two.

The telecommunications equipment that enable conference calls often doso in an imperfect manner. Part of the problem is that ateleconferencing system, with its teleconference bridge andspeakerphones, if present, has to deal with the presence of acousticecho. Acoustic echo can be introduced at each conference call locationwhen the local endpoint's microphone picks up the acoustic signals thatare emitted by the endpoint's loudspeaker and re-introduces delayedversions of audio signals already processed by the bridge.

Different techniques are used to deal with the presence of acousticecho. One such technique is automatic microphone mixing. This is used atthe teleconference bridge during the mixing process referred to earlier,in that the mixer receives signals from the endpoints involved in aconference call and determines which signals are to be passed along tothe various endpoints and which ones are to be excluded, at any givenmoment. As a result, loudspeaker-to-microphone coupling is reduced bythe amount that the automatic mixer excludes the so-called off-channels.

Another technique for dealing with the presence of echo is acoustic echosuppression, which is performed at a speakerphone. Here, thespeakerphone detects if there is sufficient enough energy in the audiosignal that arrives from a far-end participant. If there is sufficientenergy, the speakerphone essentially mutes its microphone, therebyexcluding at least a portion of any audio signals that would otherwisebe picked up by the microphone and introduced into the conference call.

A problem with these techniques is that each participant on theconference call experiences a “half-duplex” effect, in which aparticipant who is talking might think that her voice is getting throughto the rest of the participants but, in reality, is not. This oftencauses frustration on the part of the talking participant whose speechis being excluded by someone else who is also talking, particularly whenthe participant who is being excluded talks for several seconds, onlythen to find out that no one else had heard her. Additionally, dependingon each participant's acoustic environment, the type of endpoint beingused, and the manner in which the endpoint is being used, theexclusionary effect on the audio signals might occur more often for someparticipants than for others. This lopsided treatment can causefrustration for some participants even more than others on a call.

SUMMARY OF THE INVENTION

The present invention enables a participant in a conference call tomonitor, as he is speaking, whether his speech is getting through to theother participants. In accordance with the illustrative embodiment ofthe present invention, a teleconference bridge receives audio signalsfrom a group of telecommunications endpoints that are involved in aconference call. The teleconference bridge generates transmit audiosignals that are based on one or more of the received audio signals.During the ongoing process of minimizing the presence of acoustic echo,the bridge might exclude one or more of the received audio signals fromthe transmitted audio signals. When this occurs, particularly when anactive talker is being excluded, the teleconference bridge transmits anindication to one or more of the endpoints as part of one of thetransmitted audio signals. The indication can be audible such as a toneor a voice, visual such as a flashing light or displayed text, ortactile such as vibration.

In accordance with the illustrative embodiment, the bridge transmits theindication to the endpoint of the excluded active talker. In somealternative embodiments, however, the bridge can transmit the indicationto the other endpoints as well, in order to warn one or more otherparticipants that an active talker is being excluded. For example, thebridge might send the indication to an active talker whose signal is notbeing excluded, to participants who are merely listening and not talkingat that particular moment, and so forth.

By notifying the talking participant that his voice is not gettingthrough the teleconferencing equipment to the other participants, thetechnique of the illustrative embodiment is aimed at reducingfrustration on the part of the talking participant. Moreover, theillustrative embodiment empowers the excluded talking participant toquickly preempt, if necessary, another participant who is talking—forexample, by pressing a keypad key, in order to transmit a dual-tonemulti-frequency (DTMF) tone that is audible to the other participant.Alternatively, embodiments of the present invention also enable atalking participant to know when another participant is being excludedand to adjust his speaking patterns accordingly to offer the otherparticipant more chances to speak and be heard.

The illustrative embodiment of the present invention comprises:receiving, at a teleconference bridge, a plurality of receive audiosignals from a group of telecommunications endpoints that are involvedin a conference call; generating at the teleconference bridge, for thegroup of telecommunications endpoints, a plurality of transmit audiosignals that are based on at least one of the receive audio signals, inwhich one or more of the receive audio signals are excluded from atleast one of the transmit audio signals when a signal level criterion ismet; and when the one or more of the receive audio signals are excluded,transmitting to at least one of the endpoints a first audible indicationas part of one or more of the transmit audio signals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic diagram of telecommunications system 100 inaccordance with the illustrative embodiment of the present invention.

FIG. 2 depicts a flowchart of the salient tasks performed byteleconference bridge 103, in accordance with the illustrativeembodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 depicts a schematic diagram of telecommunications system 100 inaccordance with the illustrative embodiment of the present invention.System 100 comprises telecommunications network 101; telecommunicationsendpoints 102-1 through 102-N, wherein N is a positive integer greaterthan one; and teleconference bridge 103. The elements in system 100 areinterconnected as shown.

Telecommunications network 101 enables the transport and control ofcommunications signals among endpoints such as endpoints 102-1 through102-N. The communications signals convey media signals, such as audio,video, and so forth. To this end, network 101 comprises one or moreinterconnected data-processing systems such as switches, servers,routers, gateways, and teleconference bridges, as are well-known in theart. For example, network 101 comprises teleconference bridge 103.

In accordance with the illustrative embodiment, network 101 comprises anInternet Protocol-based (IP-based) network, as is known in art, for thepurpose of transmitting bitstreams of encoded voice signals. Althoughnetwork 101 in the illustrative embodiment comprises a Voice-over-IP(VoIP) service provider's network, network 101 could alternatively oradditionally comprise another type of network such as the Internet, someother type of IP-based network, or some other type of packet-basednetwork, as those who are skilled in the art will appreciate.

Telecommunications endpoints 102-1 through 102-N are telephony devices,such as speakerphones, desksets, cellular phones, soft phones residentin computers, personal digital assistants, and so forth. Each ofendpoints 102-1 through 102-N enables their users to communicate atleast audibly with one other, or with users of other endpoints supportedby network 101 that are not depicted. Accordingly, endpoints 102-1through 102-N interoperate with network 101 and with one other inwell-known fashion.

In accordance with the illustrative embodiment, endpoint 102-n, whereinn has a value of 1 through N, is a Voice over Internet Protocol (VoIP)phone. However, it will be clear to those skilled in the art, afterreading this specification, how to make and use alternative embodiments,in which endpoint 102-n is a type of endpoint other than a VoIP phone.And as those who are skilled in the art will also appreciate,embodiments of the present invention can be made and used in whichendpoint 102-n operates in various types of networks such as publicnetworks, private networks, and so forth.

Teleconference bridge 103 is a server or switch that enables the usersof multiple endpoints to communicate with one other during a conferencecall. Bridge 103 receives audio signals from endpoints that areparticipating on a conference call, mixes those signals together basedon the transfer function associated with each output channel, andtransmits the mixed signals back to the endpoints, in accordance withthe illustrative embodiment of the present invention. Bridge 103performs the tasks of the illustrative embodiment that are describedbelow and with respect to FIG. 2.

As those who are skilled in the art will appreciate, the techniques ofthe illustrative embodiment can be implemented at a device other than ateleconference bridge or at a teleconference bridge that is other than aserver or switch.

FIG. 2 depicts a flowchart of the salient tasks performed byteleconference bridge 103, in accordance with the illustrativeembodiment of the present invention. As those who are skilled in the artwill appreciate, some or all of the individual tasks depicted in FIG. 2can be performed simultaneously or performed in a different order fromthat depicted.

For pedagogical purposes, all of telecommunications endpoints 102-1through 102-N are involved in the same conference call, where N is equalto three. It will be clear, however, to those who are skilled in the arthow to make and use embodiments of the present invention in which thereis a different number of endpoints involved in the conference call(i.e., N is equal to a number other than three).

At task 201, bridge 103 receives a plurality of receive audio signals,s₁ through s_(N), from telecommunications endpoints 102-1 through 102-N,respectively, for a given conference call.

At task 202, bridge 103 generates, for the given conference call, aplurality of transmit audio signals, x₁ through x_(N) that are intendedfor endpoints 102-1 through 102-N, respectively. Each of the generatedtransmit audio signals is based on at least one of the receive audiosignals. During the course of the conference call, bridge 103 excludes,in well-known fashion, one or more of the receive audio signals from atleast one of the transmit audio signals whenever a predetermined signallevel criterion is met. In some embodiments, bridge 103 sums up, at anyparticular time, only the receive audio signals that correspond to the Mloudest talkers (e.g., M equals three, etc.) and passes that sum tolistening participants as part of the one or more transmit audio signalsgenerated.

As those who are skilled in the art will appreciate, in “excluding” aparticular receive audio signal, bridge 103 might exclude only some ofthe energy of the signal—that is, it might attenuate and/or filter thesignal rather than exclude the signal entirely. For example, in somealternative embodiments, bridge 103 performs a summation that comprisesthe receive audio signals from most or all participants, in which thesum is weighted with louder talkers being weighted more heavily thanweaker talkers.

At task 203, bridge 103 transmits, in well-known fashion, the transmitaudio signals x₁ through X_(N) to endpoints 102-1 through 102-N,respectively.

At task 204, bridge 103 determines whether one or more of the receiveaudio signals are being excluded from at least one of the transmit audiosignals. If so, task execution proceeds to task 205. Otherwise, taskexecution proceeds back to task 201.

At task 205, bridge 103 detects, in well-known fashion, whether a userof one of endpoints 102-1 through 102-N is talking. For example, bridge103 can monitor the signal energy contained in the receive audio signalsin order to determine that a user is talking. If a user is detected astalking, task execution proceeds to task 206. Otherwise, task executionproceeds to task 201.

At task 206, bridge 103 transmits to at least one of endpoints 102-1through 102-N a first indication as part of one or more of the transmitaudio signals. In accordance with the illustrative embodiment, the firstindication is an audible indication such as a tone or speech, which istransmitted only to the endpoint whose user is detected as talking. Forexample, bridge 103 transmits the first indication to endpoint 102-1when the bridge i) excludes the receive audio signal s₁ from thetransmit audio signal x₂ and ii) detects the user of endpoint 102-1 astalking. In some alternative embodiments, bridge 103 transmits anindication when it excludes the receive audio signal s₁ from thetransmit audio signal x₂, but independently of detecting the user ofendpoint 102-1 as talking.

In some other alternative embodiments, bridge 103 transmits theindication to one or more endpoints in addition to, or instead of, theendpoint whose user is detected as talking. For example, bridge 103 cantransmit a second indication to endpoint 102-1—that is, the sameendpoint as in the example in the previous paragraph—when the bridge i)excludes the receive audio signal s₂ from the transmit audio signal x₁and ii) detects the user of endpoint 102-2 as talking. And from endpoint102-2's perspective, bridge 103 can transmit another indication toendpoint 102-2 when the bridge i) excludes the receive audio signal s₂(received from endpoint 102-2) from the transmit audio signal x₁ (beingtransmitted to endpoint 102-1) and ii) detects the user of endpoint102-2 as talking.

As those who are skilled in the art will appreciate, a transmittedindication can be in the form of something other than an audible signal.For example, the transmitted indication can be in the form of a controlsignal which, for example, commands the endpoint that is receiving it toproduce a visible indication for its user.

In some embodiments, the indication (audible, visible, or otherwise) canprovide an indicium that corresponds to an endpoint whose signal isbeing excluded, an indicium such as the endpoint's telephone number, thename of the endpoint's user, and so forth. If the indication is, infact, in the form of speech, the indication can identify (i.e., “speak”)the particular user or endpoint whose audio signal is being excludedand/or ii) identify the users or endpoints that are not receiving theexcluded signal, assuming that some endpoints are receiving the signaland some are not. As those who are skilled in the art will appreciate,the particular indicium used can be derived from database informationmaintained by bridge 103 or a related node. In turn, the databaseinformation could have been obtained from the caller identificationreceived when each participant dialed into the bridge, obtained fromeach participant having spoken his or her name at the beginning of theconference call, and so forth.

After task 206, task execution proceeds back to task 201, in order tocontinue processing the conference call until the conference call isended.

It is to be understood that the disclosure teaches just one example ofthe illustrative embodiment and that many variations of the inventioncan easily be devised by those skilled in the art after reading thisdisclosure and that the scope of the present invention is to bedetermined by the following claims.

1. A method comprising: receiving, at a teleconference bridge, aplurality of receive audio signals from a group of telecommunicationsendpoints that are involved in a conference call; generating at theteleconference bridge, for the group of telecommunications endpoints, aplurality of transmit audio signals that are based on at least one ofthe receive audio signals, in which one or more of the receive audiosignals are excluded from at least one of the transmit audio signalswhen a signal level criterion is met; and when the one or more of thereceive audio signals are excluded, transmitting to at least one of theendpoints a first audible indication as part of one or more of thetransmit audio signals.
 2. The method of claim 1 further comprisingdetecting, in at least one of the receive audio signals, whether a userof one of the endpoints is talking, wherein the transmitting of thefirst audible indication occurs only when the user is detected astalking.
 3. The method of claim 2 wherein the transmitting of the firstaudible indication is to an endpoint whose user is detected as talkingand whose receive audio signal is being excluded.
 4. The method of claim3 wherein the first audible indication is in the form of a tone.
 5. Themethod of claim 2 wherein the transmitting of the first audibleindication is to an endpoint whose receive audio signal is not beingexcluded.
 6. The method of claim 2 wherein the first audible indicationprovides an indicium that corresponds to an endpoint whose audio signalis being excluded.
 7. The method of claim 6 wherein the first audibleindication is in the form of speech.
 8. The method of claim 1 furthercomprising transmitting, to at least one endpoint in the group, a secondindication in the form of a control signal, wherein the control signalcommands the at least one endpoint to produce a visible indication.
 9. Amethod comprising: receiving, at a teleconference bridge, a plurality ofreceive audio signals from a group of telecommunications endpoints thatare involved in a conference call, the plurality comprising a receiveaudio signal s₁ from a first endpoint and a receive audio signal s₂ froma second endpoint in the group; detecting in the receive audio signal s₁whether the user of the first endpoint is talking; generating at theteleconference bridge, for the second endpoint, a transmit audio signalx₂ that is based on at least one of the receive audio signals, in whichone or more of the receive audio signals are excluded from the transmitaudio signal x₂ when a signal level criterion is met; and transmitting afirst indication to the first endpoint when i) the receive audio signals₁ is excluded from the transmit audio signal x₂ and ii) the user of thefirst endpoint is detected as talking.
 10. The method of claim 9 whereinthe first indication is in audible form.
 11. The method of claim 10wherein the first indication is in the form of a tone.
 12. The method ofclaim 10 wherein the first indication is in the form of speech.
 13. Themethod of claim 9 wherein the first indication is in the form of acontrol signal.
 14. The method of claim 13 wherein the control signalcommands the second endpoint to produce a visible indication.
 15. Themethod of claim 9 further comprising: detecting in the receive audiosignal s₂ whether the user of the second endpoint is talking; andtransmitting a second indication to the second endpoint when i) thereceive audio signal s₁ is excluded from the transmit audio signal x₂and ii) the user of the second endpoint is detected as talking.
 16. Themethod of claim 15 wherein the second indication provides an indiciumthat corresponds to an endpoint whose signal is being excluded.
 17. Amethod comprising: receiving, at a teleconference bridge, a plurality ofreceive audio signals from a group of telecommunications endpoints thatare involved in a conference call, the plurality comprising a receiveaudio signal s₁ from a first endpoint and a receive audio signal s₂ froma second endpoint in the group; detecting i) in the receive audio signals₁ whether the user of the first endpoint is talking, and ii) in thereceive audio signal s₂ whether the user of the second endpoint istalking; generating at the teleconference bridge, for the secondendpoint, a transmit audio signal x₂ that is based on at least one ofthe receive audio signals, in which one or more of the receive audiosignals are excluded from the transmit audio signal x₂ when a signallevel criterion is met; and when the receive audio signal s₁ is excludedfrom the transmit audio signal x₂, transmitting i) a first indication tothe first endpoint when the user of the first endpoint is detected astalking and ii) a second indication to the second endpoint when the userof the second endpoint is detected as talking.
 18. The method of claim17 wherein the first indication is in audible form.
 19. The method ofclaim 18 wherein the first indication is in the form of a tone.
 20. Themethod of claim 18 wherein the first indication is in the form ofspeech.